Sheet feeding device



July 17, 1962 T. P. c. BREUERS 3,

SHEET FEEDING DEVICE Filed Jan. 27, 1961 INVENIOR THEO PIERRE CHRETIEN BREUERS BY Ma. W

ATTORNEY United States atent Claims priority, application Netherlands Feb. Z, 1960 3 Claims. (Cl. 27 136) The invention relates to a device for feeding out, one by one, sheets of laminar material, such as paper, cardboard, and the like, which together form a stack, said device comprising a positively driven conveyor member and a movable friction member cooperating under pressure with the conveyor member and acting upon the sheets, the cooperating parts of which members move along closed tracks and between which members the sheets are fed out, the direction of movement of the friction member being dependent on the possible presence between friction member and conveyor member of at least two superimposed sheets of laminar material, and the friction between friction member and laminar material as well as the friction between conveyor member and laminar material being greater than the friction between two sheets of laminar material.

In United States patent specification No. 2,892,629 a device is known which comprises a positively driven conveyor roller and a friction roller pressing against the conveyor roller. The friction roller is connected with one end of a helical spring, while the other end of the helical spring is connected with the frame of the device via a slip clutch. In this device the sheets are pushed from the stack and fed into the nip between conveyor roller and friction roller by means of a feed roller.

The slip clutch and the pressure between friction roller and conveyor roller are adjusted in such a way that if only one sheet gets between friction roller and conveyor roller, the sheet is taken along by the conveyor roller and fed out. The sheet in its turn drives the friction roller. The helical spring is thus wound up and tensioned. When the tension of the spring has risen to a maximum permissible value, the slip clutch will slip. The spring thus tensioned tends to drive the friction roller in a direction opposite to that in which the'sheet fed through is moving and consequently exerts a retarding action on the said sheet.

However, if two sheets at a time get between friction roller and conveyor roller, only the sheet coming into contact with the conveyor roller is fed out. The movement of the other sheet is counteracted by the retarding action of helical spring and friction roller. The friction between the two sheets being rather small in comparison with the friction between one sheet and the conveyor'roller and in comparison with the friction between the other sheet and the friction roller, the helical spring now drives the friction roller, and thus the sheet in contact with the friction roller is rubbed back by the friction roller beyond the nip between friction roller and conveyor roller and detained there until the other sheet has passed altogether through the device.

When this known device is used in practice, difficulties may be encountered. Indeed, if two sheets get between friction roller and conveyor roller and the helical spring has not (yet) been tensioned sufl'iciently, the retarding action of the friction roller is too small. In such a case both sheets will pass through the device. If, on the other hand, the spring has been tensioned suiiiciently, it may happen that the friction roller does rub back one sheet beyond the nip between friction roller and conveyor roller, but then, while the other sheet has not yet been fed out altogether, is not immediately arrested because of the uncontrolled release of the spring, but continues counterrotating until the spring has been released almost entirely. The sheet that has been rubbed back can then still be fed through the device together with the sheet that has already been partly fed out. Moreover, it is a great disadvantage of the known device that the capacity of the helical spring is limited. When handling a stack of sheets which adhere somewhat to each other (eg due to static electricity or deformed edges), two or more sheets at a time may repeatedly get between friction roller and conveyor roller. The helical spring will soon be released under such conditions.

Another disadvantage of the known device is that, if the spring has been fully tensioned, the friction roller exerts a retarding force which is greater than the force that is required for the rubbing-back, because, if it were not so, this force might soon fall below the minimum necessary value during the release of the spring.

It is the object of the present invention to provide an improved device for the purpose indicated. The device according to the present invention is equipped with continuously operating driving members for the friction member, and a slip clutch between the driving members and the friction member, said driving members continuously tending to drive the friction member via the slip clutch with a force which is always sufficient to overcome the friction between two sheets of laminar material in a direction opposite to the direction in which it is influenced by the conveyor member.

As compared with the known device, the device according to the invention, owing to the continuously operating driving members, has the advantage that the friction member is always able to exert a retarding action with a constant force. A reliable operation is thus obtained, even if sheets adhering to each other are handled, and even if repeatedly some of them are simultaneously fed between friction member and conveyor member, and the friction member has to move almost continuously contrary to the movement of the conveyor member.

To ensure reliable operation it is naturally necessary for the device to be adapted to the nature of the sheets to be handled. Generally speaking, its construction should be such that the driving force which is exerted on the friction member via the slip clutch is greater than the driving force exertedby the conveyor member (if two or more sheets are present between this member and the friction member) on the friction member via these sheets, but

smaller than the driving force exerted by the conveyor member if only one sheet or none at all is present between conveyor member and friction member.

if, in a device according to the invention of the above construction, one sheet is present between friction member and conveyor member, the sheet is taken along by the conveyor member. In consequence of the friction between the sheet and the conveyor member and of the friction between the sheet and the friction member, the sheet thus fed through drives the friction member. Those parts of the two members which press against the sheet then move in the same direction and the sheet is fed out. The slip clutch between the driving members and the friction member will then slip. In consequence a retarding action is exerted on the sheet fed through, which, however, does not prevent the forward movement of the sheet.

If two superimposed sheets get between friction member and conveyor member and if the force necessary to make these sheets slide on each other is comparatively small, the sheet coming into contact with the conveyor member is taken along by this member and fed out. The driving force which the conveyor member is now able to exert on the friction member via the two sheets being only small, the friction member will start moving in the opposite direction under the influence of the continuously driven slip clutch. The sheet present between the sheet fed through and the friction member is rubbed back and detained until the other sheet has been fed out altogether.

If more than two sheets get between friction member and conveyor member, only the sheet in contact with the conveyor member is fed out. All the other sheets are rubbed back successively by the friction member, which in the meantime has started moving in the opposite direction again.

If the leading edges of the sheets which have got between conveyor member and friction member do not coincide, but the sheet turned towards the friction member has an edge projecting beyond the other sheet (to be fed out first), the projecting sheet will at first be gripped by the conveyor member and will be fed further. It is not until the other sheet has moved so far that it has arrived in the zone between friction member and conveyor member that the movement of the friction member will change direction. The sheet with the projecting edge is then rubbed back, while the other sheet is fed further. If one sheet projects far beyond the other sheet, it might not have been rubbed back altogether when the other sheet has already been passed through altogether. The sheet that is rubbed back would then be gripped again by the conveyor member, and be fed out while partly overlapping the sheet which has already been passed through. Such overlapping may cause difficulties during the further handling of the sheets. In order to prevent such difficulties, the device according to the invention is preferably so constructed that the velocity of rotation of the driving member of the slip clutch has such a value that the circumferential speed of the friction member, when being driven via the slip clutch, is considerably greater than the circumferential speed of the conveyor member (1.5-3 times as large, for instance).

The device being adjusted in such a way that the direction of movement of the friction member is not reversed until at least two sheets are present between said member and the conveyor member, the friction member counteracting at great speed cannot do damage to the sheets. Even sheets carrying easily damaged texts or images can be fed through the device without risk of damage.

Specific embodiments of apparatus according to the present invention are illustrated in the accompanying drawings, in which:

FIGURE 1 is a diagrammatical longitudinal section of a device according to the invention, with which invariably th lowermost sheet of a stack of sheets is fed out.

FIGURE 2 is a diagrammatical cross-section of the device according to FIGURE 1.

FIGURE 3 is a diagrammatical longitudinal section of a device according to the invention, in which upon feedingout of the sheets it is invariably the uppermost sheet of the stack which is fed out.

The device according to FIGURES 1 and 2 is provided with a conveyor roller 1, which has a cover of wearresistant elastic rubber. With the aid of driving members (not shown) the roller 1, which is supported in stationary bearings in frame 2, is continuously driven as indicated by an arrow. Shaft 3, on which some friction discs 4 are mounted at distances of 10 cm., for instance, is supported in frame 2 so as to be vertically movable. The friction discs 4, which rest against the cover of roller 1 under pressure caused by their own weight and the weight of shaft 3 and of the parts (to be mentioned hereinafter) connected with siiaft 3, have a cover of Vulkollan (polyurethane of Bayer A.G., Leverkusen, Germany).

Mounted on a journal of conveyor roller 1 extending through frame 2 is a wheel 5, which is provided with a toothed rim cooperating with the teeth of pinion 6. Pinion 6 cooperates with a gear wheel 8, which is adapted to rotate on journal 7 of the shaft 3. When roller 1 is driven, gear wheel 8 rotates as indicated by the dotted arrow.

Gear wheel 8 forms part of a slip clutch system mounted on journal 7, which furthermore comprises slipping discs 9 and E3, clutch discs 11 and 12, spring 13, and nut 14. Clutch disc 11 is rigidly connected with journal 7; clutch disc 12 is equipped with a projecting key, adapted to slide in a slot in journal 7. Consequently clutch disc 12 can be moved in the axial direction on journal 7. Nut 14 can be moved over the threaded end of journal 7, and thus the degree of compression of spring 13 can be varied by means of nut 14, and consequently the value of the couple which is transmitted to shaft 3 via the slip clutch and which naturally has to be adapted to the nature of the sheets to be handled, can be adjusted.

The diameters of roller 1, friction discs 4, wheel 5 and gear wheel 3 have been so chosen that the circumferential peed of the discs 4 is about one and a half times as neat as the circumferential speed of roller 1.

If on the curved table 15, which slopes downwards in the direction of delivery, a stack of sheets 16 is arranged, of which the lowermost sheet extends with one edge into the nip between conveyor roller 1 and friction discs 4,

this sheet is gripped and taken along by the rubber cover of roller 1. Owing to friction between the sheet and the covers of friction discs 4 the sheet also exerts a driving force on the friction discs. This force counteracts the couple which acts on the friction discs via the slip clutch and shaft 3 described above.

However, the slip clutch has been adjusted in such a way that the couple exerted by it is too small to overcome the friction between the sheet and the friction discs. Consequently the friction discs turn with the sheet, while the slip clutch, which continuously tends to drive discs 4 in the opposite direction, will slip.

The sheet taken along in this way is fed to the rollers 13 and 19 via the guiding member 17. Roller 13, which is supported in stationary bearings, is driven continuously via rope 20, which lies in a groove of wheel 5 and a rope pulley on the journal of roller 18. Roller 19, which is supported in bearings so as to be vertically movable, under the influence of its own weight rests on roller 13 and thus is also driven continuously. These rollers grip the sheet passing over guiding member 17 and feed it out.

Above table 15 an arresting plate 21, which extends the full width of the device with its lowermost edge parallel to and at a short distance from the feeding table, is mounted in such a way that near the nip between friction member and conveyor member a narrow slit is present between the lower edge of the arresting plate and table 15.

If the lowermost sheet of stack 16 is fed out in the manner described above, the remainder of the stack (which rests on the lowermost sheet) is fed against plate 21. A limited number of sheets may, however, pass through the slit between table 15 and plate 21 along with the lowermost sheet and thus enter the nip between conveyor roller 1 and friction discs 4.

If in this way two sheets get between conveyor roller 1 and friction discs 4, the (lowermost) sheet coming into contact with the roller is fed further. Now roller 1 is no longer able to exert suflicient driving force on friction discs 4 via the sheets, because the friction between the sheets is too small. The friction discs are then no longer driven by roller 1, but by the slip clutch. In consequence their movement changes direction. Owing to friction the sheet coming into contact with the friction discs is taken along by the friction discs and thus rubbed back beyond the nip between roller 1 and discs 4. It is not until the lowermost sheet has passed completely between roller 1 and friction discs 4 that the sheet which has been rubbed back is able to pass between roller 1 and discs 4 again. If more than two sheets at a time pass through the slit between table 15 and plate 21 and get between conveyor roller 1 and friction discs 4, the lowermost of them is fed out normally, while all the other sheets are rubbed back successively by the friction discs.

It may of course happen that it is not the lowermost sheet which first reaches the nip between conveyor roller and friction discs, but a sheet lying higher up. This sheetwill then at first be taken along by the conveyor roller. However, as soon as the lowermost sheet also reaches the conveyor roller and the friction discs start counter-rotating, the sheet lying higher up is rubbed back again.

The device described above has a simple construction and is extremely suitable for feeding out one by one sheets which together form a loose stack of not too great a size. It is suitable, for instance, for automatically feeding documents or transparent originals to continuously operating photographic reproduction apparatus.

It has the additional advantage that new originals can repeatedly be laid on the sloping table without it being necessary to interrupt the feeding of originals or to stop the reproduction apparatus. It is also a very attractive feature that the originals are fed out and copied in the same sequence in which they are put in the apparatus, because it is always the lowermost sheet which is taken from the stack.

FIGURE 3 is a diagrammatical illustration of a device according to the invention, by means of which large stacks of sheets can be handled. This device comprises a conveyor roller 1 supported in stationary bearings in frame 2 and driven (by members not shown) in the direction of the arrow, and a friction disc 4 resting against roller 1 under pressure. The shaft of friction disc 4 rests in bearings 22, adapted to slide in slots in frame 2. With the aid of adjusting screws 23 the compression of the helical springs 36 can be varied, and thus the pressure between friction disc 4 and conveyor roller 1 can be adapted to the nature (smoothness and evenness of the surface) of the sheets to be handled.

Mounted on the journal of the shaft, passing through the frame, on which disc 4 is fixed, is an adjustable slip clutch system which cooperates with a gear wheel fixed on the journal of conveyor roller 1; these features are similar to those of the device according to FIGURES l and 2. Friction disc 4 accordingly is influenced by a driving force, which is exerted by roller 1, and a couple counteracting this force, which is caused by the slip clutch.

Friction disc 4 and conveyor roller 1 are both covered with a high-friction, somewhat elastic, and wear-resistant material.

Also mounted in stationary hearings in frame 2 is a rubber-covered feed roller 24, which is driven continuously with the aid of rope 25 and the rope pulleys 26 and 27, which are fixed on journals of the rollers 1 and 24 respectively. The stack of sheets 16 to be fed out is put on a table 28 that is movable in the vertical direction. Table 28 is fitted with sliding sleeves 29, adapted to slide on stationary bars 30, and with an elongated rack 31. With the aid of a gear wheel 32 engaging with rack 31 an upwardly directed force is continuously exerted on table 28, in consequence of which invariably the uppermost sheet of stack 16 is forced against roller 24. Gear Wheel 32 is continuously influenced for this purpose, by a motor via a slip clutch, for instance. The vertical plate 33 acts as a stop when the sheets to be handled are put in the apparatus.

Feed roller 24 continuously pushes sheets from stack 16 to the nip between conveyor roller 1 and friction disc 4. The quantity of sheets is limited by the width of the slit between conveyor roller 1 and the curved upper end of plate 33.

With the aid of adjusting screws 26 and the nut of the slip clutch system the device is adjusted in such a way that the friction disc is driven by the conveyor roller if one sheet is present between conveyor roller and friction disc, but that the friction disc is driven in the opposite direction by the slip clutch if two or more sheets are present between conveyor roller and friction disc.

If one sheet is thus pushed from stack 16 by roller 24, this sheet is gripped by conveyor roller 1 and fed out via the guiding members 34 and 35. If roller 24 pushes several sheets at a time between conveyor roller and friction disc, only the uppermost sheet is fed out, while the other sheets are rubbed back successively by the counter-rotating friction disc.

The device according to FIGURE 3 is suitable for successively feeding out large numbers of sheets of laminar materiaL- With the aid of adjusting screws 23- and the nut on the slip clutch, the device can be adjusted for handling sheets of several kinds, which vary widely in respect of smoothness and evenness.

The device is extremely suitable as a sheet-feeding device forming part of or being used in apparatus for handling sheets, such as photoprinting apparatus and ofiset printing machines.

The conveyor member used in the devices described above is a conveyor roller. Other members, such as a conveyor belt or a number of parallel endless belts, may be used as conveyor members. Instead of the friction discs described above, friction rollers or belts may also be employed.

I claim:

1. Device for feeding out, one by one, sheets of laminar material, which together form a stack, said device comprising a positively driven conveyor member and a movable friction member cooperating under pressure with the conveyor member, the cooperating parts of which members move along closed tracks and between which members the sheets are fed out, the direction of movement of the friction member being dependent on the possible presence between the friction member and the conveyor member of at least two super-imposed sheets of laminar material, while the friction between the friction member and one of the sheets as well as the friction between the conveyor member and one of the sheets is greater than the friction between two of the sheets, continuously operating driving means for the friction member, including driving members and a slip clutch between the driving members and the friction member, continuously tending to drive the friction member via the slip clutch, with a force which is always suificient to overcome the friction between two of the sheets of laminar I material, in a direction opposite to the direction in which the friction member is influenced by the conveyor member.

2. A device according to claim 1, said driving means being operative with a speed of rotation such that the circumferential speed of the friction member, when being driven via the slip clutch, is considerably greater than the circumferential speed of the conveyor member.

3. A device according to claim 1, which further comprises a feeding table sloping downwards in the direction of delivery of the sheets and, mounted above said table near the nip between the friction member and the conveyor member, an arresting plate the lowermost edge of which extends parallel to and at a short distance from the feeding table.

Uthenwoldt et a1 Sept. 11, 6 Mentzer Nov. 19, 1957 Notice of Adverse Decision in Interference In Interference N0. 94

,203 involving Patent No. 3,044,770, T. P. C. Breuers, SHEET FEEDING DEVICE, final judgment adverse to the patentee was rendered Oct. 21, 1965, as to claim 1.

[O ficial Gazette May 17', 1.966.] 

